Improving the corrosion resistance of Fe-21Cr-9Mn alloy in liquid zinc by heat treatment

•Oxidizing and nitriding-oxidizing treatment were performed for Fe-21Cr-9Mn alloy.•These two heat treatments can protect the matrix from corrosion in liquid zinc.•The alloy after nitriding-oxidizing treatment shows a best corrosion resistance.•The reason is that the formation of the more compact and intact oxide structure.•Corrosion of the modified alloy is caused by dissolution and localized corrosion.

The effects of oxidizing treatment (OT) and nitriding-oxidizing treatment (NOT) on the corrosion resistance of Fe-21Cr-9Mn alloy in liquid zinc were investigated. The results reveal that they both can significantly improve the corrosion resistance owing to the presence of an unwettable oxide layer. By comparison, NOT alloy shows a longer incubation time in liquid zinc than OT alloy due to a more high-quality oxide. The corrosion of these two modified alloys both are controlled by dissolution mechanism and localized corrosion of the oxide.